This invention relates to biodegradable lubricant compositions made from vegetable oil triglycerides and antioxidants. These lubricant compositions can be used for lubricating engines, transmissions, gear boxes, and for hydraulic applications. These compositions provide antioxidant stability as well as cold temperature performance. These compositions can also be used as a base stock for biodegradable greases or any other biodegradable lubricant compositions requiring oxidation stability, such as a transformer oils, penetrating compositions, corrosion inhibition compositions and metal working compositions.
Vegetable oils are obtainable in large volumes from renewable resources and in general are characterized as readily biodegradable or xe2x80x9cenvironmentally friendly.xe2x80x9d As a result, such oils are potentially attractive for use in a wide variety of applications.
With respect to use for lubrication purposes, vegetable oils have not been fully desirable. Many vegetable oils do not possess the desired spectrum of characteristics relating to: pour point; oxidative stability; and compatibility with additives among others. Vegetable oils do however possess many desirable properties for use as a lubricant. In particular, vegetable oils typically provide good boundary lubrication, good viscosity, high viscosity index and high flash point. In addition, vegetable oils are generally nontoxic and readily biodegradable. For example, under standard test conditions (e.g., OCED 301D test method), a typical vegetable oil can biodegrade up to 80% into carbon dioxide and water in 28 days, as compared to 25% or less for typical petroleum-based lubricating fluids.
U.S. Pat. No. 4,783,274 (Jokinen et al., Nov. 8, 1988) is concerned with an anhydrous oily lubricant, which; is based on vegetable oils, which is substituted for mineral lubricant oils, and which, as its main component, contains triglycerides that are esters of saturated and/or unsaturated straight-chained C10 to C22 fatty acids and glycerol. The lubricant is characterized in that it contains at least 70 percent by weight of a triglyceride whose iodine number is at least 50 and no more than 125 and whose viscosity index is at least 190. As its basic component, instead of or along with the said triglyceride, the lubricant oil may also contain a polymer prepared by hot-polymerization out of the said triglyceride or out of a corresponding triglyceride. As additives, the lubricant oil may contain solvents, fatty acid derivatives, in particular their metal salts, organic or inorganic, natural or synthetic polymers, and customary additives for lubricants.
U.S. Pat. No. 5,538,654 (Lawate et al., Jul. 23, 1996) describes a food grade lubricant composition which is useful as hydraulic oil, gear oil, and compressor oil for equipment in the food service industry. This composition comprises (A) a major amount of a genetically modified vegetable oil and (B) a minor amount of a performance additive. In other embodiments the composition contains either (C) a phosphorus compound or (D) a non-genetically modified vegetable oil.
U.S. Pat. No. 5,580,482 (Chassan et al., Dec. 3, 1996) relates to a lubricant composition stabilized against the deleterious effects of heat and oxygen said composition comprising a triglyceride oil or an oil which is an ester wherein unsaturation is present in either the alcohol moiety or the acid moiety and an effective stabilizing amount of either an N,N-disubstituted aminomethyl-1,2,4-triazole or an N,N-disubstituted aminomethylbenzotriazole and a higher alkyl substituted amide of dodecylene succinic acid.
U.S. Pat. No. 5,888,947 (Lambert et al., Mar. 30, 1999 relates to a composition that has three main components: a base oil, an oil source containing hydroxy fatty acids and an oil source containing vegetable or animal waxes. The base oil used in the reference needs to consist of primarily triglycerols (triglycerides) and mono- and diglycerols (glycerides) and free fatty acids. The composition further consists of vegetable oils where the glycerols contain hydroxy fatty acids, preferably making up 5% to 20% of the oil. A third major component is waxes composing 5% to 10% of the oil additives by volume. Additional synthetic mimics or natural products derived from animal or vegetable compounds may be added up to 5% of the compositional volume.
U.S. Pat. No. 6,300,292 (Konishi et al., Oct. 9, 2001 relates to a hydraulic oil composition comprising vegetable oil with a total degree of unsaturation of 0.3 or less as base oil, and comprising at least one antioxidant selected from the group consisting of a phenol antioxidant, an amine antioxidant and a zinc dithiophosphate antioxidant in an amount of 0.01 to 5% by mass based on the total amount of the composition.
U.S. Pat. No. 6,312,623 (Oommen et al., Nov. 6, 2001) is directed to an electrical insulation fluid comprising at least 75% of a high oleic acid triglyceride composition that comprises fatty acid components of at least 75% oleic acid, less than 10% diunsaturated fatty acid component; less than 3% triunsaturated fatty acid component; and less than 8% saturated fatty acid component; and wherein said composition is further characterized by the properties of a dielectric strength of at least 35 KV/100 mil gap, a dissipation factor of less than 0.05% at 25xc2x0 C., acidity of less than 0.03 mg KOH/g, electrical conductivity of less than 1 pS/m at 25xc2x0 C., a flash point of at least 250xc2x0 C. and a pour point of at least xe2x88x9215xc2x0 C., and one or more additives selected from the group of an antioxidant additive, a pour point depressant additive and a copper deactivator.
A composition, comprising;
(A) at least one triglyceride oil of the formula 
xe2x80x83wherein R1, R2 and R3 are aliphatic hydrocarbyl groups containing from about 7 to about 23 carbon atoms and
(B) a combination of antioxidants comprising
(1) two amines of the formula 
xe2x80x83and R5 is hydrogen, an alkaryl group or an aralkyl group, R6 is an aryl group, an alkaryl group or an aralkyl group, with the proviso that when R5 is hydrogen, then R4 is an aryl group and
(2) a phenol of the formula 
xe2x80x83wherein R13 is an alkyl group containing from 1 up to about 24 carbon atoms and a is an integer of from 1 up to 5.
Optionally, the (A) and (B) composition may further comprise
(C) other oils comprising
(1) a synthetic ester base oil,
(2) a polyalphaolefin or
(3) unrefined, refined or rerefined oils, and mixtures of (C) (1) to (C) (3).